MTC MVX Skimmer review

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jason2459

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Don't know if I've really noticed to much production wise with the 5" extension to make it a 42" skimmer but amazingly enough I have noticed about a .02-.04 value increase in pH. The air draw is about the same as before adding the extension but is about 10gph less flow. So, I'm thinking even the little extra height with the little slower flow which slightly increases the dwell time between both of those factors is enough to aerate the water just that slightly better.

I'm going to slap on the 784 mazzei injector tonight or tomorrow. See what happens.
 
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784 mazzei injector is now in place. And now that I have a flow meter in place I can validate it is infact pretty much 100gph more flow then the 684. FYI the model number = rated flow rate.

With the 684 mazzei I was pushing though about 280-290gph (290-300gph before extension). With the 784 mazzei in place its showing around 390gph flow rate.

f847d5d530b3084f68e3db67c0726b6f.jpg


But it's only pulling in like 2-4 more scfh. From 29-30 to 32-34scfh. The extra flow makes the top much more turbulent so the 784 just is not well balanced IMO. Maybe for a much taller skimmer. Unless you like a wet skimmate which this certainly produces more of compared to the 684.

Pretty much what I also observe with the life reef skimmers with the 978 stock or the 1078 some have put on. Lots of flow and more tubulent which makes what I seem to see more often is a wetter skimmate. I'm not saying that's wrong but not what I feel is beter. I know there's arguements for wet skimmate as well.

But back to lifereef skimmers for a second. It seems Jeff from lifereef must balance that large amount of flow by slamming it into the bottom of the skimmer into that litte cylinder to cut down somewhat on the turbulence up top and balances it out a little more again with the smaller neck. I always thought it was smaller just to fit it next to the intake. But now I'm thinking there's more to it then that. I still feel like the contact time is impacted by that design.

I'm still much happier with the design and performance of the MTC MVX over the lifereef and so happy I went this route. Both are good and both have great guys building them and just so happens they are both called Jeff. lol

I'll go ahead and let this run a few days as I don't feel like changing anything right now. But I want to try out the 584 mazzei next.
 
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jason2459

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Well, maybe I was wrong and to quick to judge. Based on what I saw last night there was a lot of turbulence up top the skimmer like I had normally seen before adding the extension.

This morning on my normal checks that turbulence has settled down completely and looks normal now. So, maybe that extension did help. I'll have to keep an eye on it and observe over the next couple weeks now. I was just going to leave it running for a few days expecting what I experienced before. But now if it keeps reacting the same as it is this morning that's great.

I do not expect an increase in skimmate production which I've long past stopped caring so much about after hitting what seems like a limit of around 6 to 8 cups per day of dry sticky goodness. But what I would like more and more of is better aeration. I'll have to look back but previously the 784 had a slight decrease in pH which I believed was because of the flow rate being to high and not getting enough contact time. So, over the next couple weeks I'll see how the pH reacts over time. This morning pH is .06 higher then it was yesterday morning. That's a pretty significant (though extremely small amount) increase in pH just after changing that mazzei out.

Will see what happens and see if this morning is a fluke or not. If instability is created then the slight gain in aeration is not worth it.


.06 pH increase over last night's low. 2 pH probes to confirm each other's readings.
76bef21123bdc395489e8b0a42606390.jpg
 
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Kept spot checking last night and again this morning. I also shut it down and back on a few times.

With the 784 mazzei and my new skimmer's height it seems like right after start up the turbulence is quite a lot. Except, with the extension now it seems to be able to settle down with in an hour or so. Very interesting.

pH is definitely boosted counter to the previous run with the 784. Crazy what just going from 36" to 42" can do. I would definitely say if using a taller 48+" the 784 maybe worth a try. 36" the stock 684 seems perfectly balanced.

Will keep watching but happy to see pH boosted again.
a6bf6cb8f14bf7bd0fb6531424a487c6.jpg
 

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Interesting concept on the lifereef design, but the design is actually to reduce the turbulence at the bottom of the skimmer so that the water slows down to allow the bubbles to rise. If you look at the way the lifereef skimmer is designed, if the inner tube was to low some of the bubbles would escape, if the inner tube was to high it would cause turbulence at the top of the skimmer. ( (Yes I am LifeReef owner :) , and had a MTC a long time ago (It was the first skimmer I ever used))

I am following this very interesting thread, as skimming is a simple principle of contact time within the chamber, size of the bubbles and the neck design at the top, and seeing your different configurations and output is quite informative and enjoy seeing the results.
 
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Thanks for following my crazy adventure with a simple skimmer.

Yep, I agree the inner cylinder seems to serve to help reduce turbulence and escaping microbubbles.

....

But back to lifereef skimmers for a second. It seems Jeff from lifereef must balance that large amount of flow by slamming it into the bottom of the skimmer into that litte cylinder to cut down somewhat on the turbulence up top and balances it out a little more again with the smaller neck. I always thought it was smaller just to fit it next to the intake. But now I'm thinking there's more to it then that. I still feel like the contact time is impacted by that design.

I'm still much happier with the design and performance of the MTC MVX over the lifereef and so happy I went this route. Both are good and both have great guys building them and just so happens they are both called Jeff. lol
...
 
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Over a month now with the 42" body, jebao dcp 18000, and 784 mazzei. It's been kicking butt the entire time. Definitely the most powerful combo to date.

With the 1/2" barb and air tubing setup its certainly not quite and with the flow of the 784 mazzei and power of the dcp18000 it certainly has a lot of microbubbles escaping. But holy crud is it producing. And a lot more consistently then I thought it would as I didn't get consistent results previously with the 784 mazzei. With my sump setup the microbubbles are not an issue at all and being in the basement the noise is no problem.
 
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Minor update. Works been backing me up and haven't been able to play with this much at all. I did have to pull the jebao dcp 18000 to clean last week. It was still pushing but was slowing down. Flow meter let me know as did the fact I had to close the output valve a bit to bring the water level up a bit.

I found the pump very easy to take apart and clean and it really needed it. Probably doesn't help I don't use any filter socks or mechanical filtration and let detritus build up in the sump and carbon dose. It was fully coated in brownish slime.

Otherwise I have not cleaned out the mazzei venturi intake once in I do not remember when. Probably helps I do have the grate that comes with the pump on the intake so larger things like a small snail or rock can't get up in there. Also, my skimmer does turn off a few times a day for feeding and flushes the venturi out.

I also haven't gotten around to cleaning the collection cup out since...I don't remember again. Been a while. The neck cleaner had been doing great and the skimmers still producing like crazy and aerating perfectly.

pH still way up there with the dcp 18000
32b2afa18dcf50155b36c1b50d0f8689.jpg
 

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I've been looking for a new skimmer to help with the aeration of my system, 220DT 265 total volume. Thank you very much for documenting all of your testing here, it's very helpful and this looks like one heck of a skimmer!

I've been trying to make heads and tails of the flow and air draw numbers your seeing. Based on Mazzie's charts, that I've attached for everyone, the air draw is based heavily on operating psi of the water on the inlet side of the injector. Most of the pumps available to us don't operate at higher psi numbers. This is why the draw didn't jump up when running dual injectors. You'd need a pump that could produce higher psi at the inlet or run a pump for each injector. I don't think either of those options are very good for us.

Based on the flow you're getting on the 684 at 290gph/4.8gpm, Mazzie's chart shows that to be about 10-12psi at the inlet. On the 784 at 390gph/6.5gpm it's right in that same 10-12psi range. What's confusing to me is the fact you're pulling air at a rate that would equal a higher psi, 25-30 on the 684 and 15-20 with the 784. This is especially true if there's any pressure on the outlet side, where the draw drops quickly at even 1-5psi. In which case the inlet pressure would have to be even higher to hit the draw you're getting. Do you think the removal of the spring & ball opens up the air draw enough to make that much of a difference or do you think there something else going on?
 

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anit77

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I just spoke with Jeff. He's going to make me one with a 32" main chamber which will give it a 48" overall height. Now I just need to nail down the injector and pump combo I want to go with. I'm leaning heavily towards the DCP-18000 and 784 Mazzei. There just isn't another pump in that price range that can put out that much flow, even if it's only putting out 90% of what it rated for. I currently have a DCT-15000 for my main pump & a DCP-6000. Been planning on getting a 18000 for the main, I guess now I'll just buy 2 ;)
 

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Looking to see what everyone thinks about this setup.

The skimmer is going to run external and I have some thought's on how I'm going to set up the plumbing to maximize performance.

I'm going to build a stand for the skimmer so it sits just higher than my sump, which sits on the floor in my basement, so the height at the base allows for the supply & return lines to clear the top of the sump. I'm going to be running a DCP-18000 pump that will be in the drain chamber of the sump. For the supply plumbing I'm going to come off the pump with 1-1/2" PVC and route it up and out of the sump then run horizontally directly to the inlet of the skimmer. I will step down the PVC to 1" for a Neptune flow meter then attach the injector next a few inches before entering the skimmer base. The injector will be installed with the air inlet facing down, so whenever the pump is turned off water will flow through it. I believe that by using larger diameter pipe off the pump and the total length of the piping being 4.5' or less before the skimmer inlet it will greatly reduce the head pressure on the pump.

I just don't know how large of an injector I can get away with before it's supplying to much flow. I know Lifereef skimmers use a 1" Mazzei so I was thinking about using an 878, 885x or 978. There just very little info out there about sizing. I'm hoping I could get away with at least an 800 series. If so I can have Jeff set the inlet up to accept 1" pipe (if it's not 1" already) and use this Tee inside the skimmer. Going this route could push the water flow upwards of 500+gph and have an air draw over 40scfm.

Do you think going with a 1" injector will supply too much flow for this size skimmer or could one of the 800 series injectors be right in the sweet spot?
 
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Sorry very busy at work. I know I have some PMs too.

I would not go 1". The 784 is a lot of flow and the stock 684 does a fine job.

The lifereef slams down into that cup section in the skimmer to kill the flow. I much prefer the MVX design.

I'd be very interested in your results though if you do go with a 1" injector.
 

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It's cool, no worries.

Is the pipe that comes on the skimmer 1", other than the injector that is? It's hard to tell from the pics.

I think your right, I'm going to start with a 784. With a lot less piping my flow numbers should be up as it is. If you're hitting 390gph now, with only one elbow in my design (and it's going to be 1-1/2" if I don't just go spa-flex to the flow meter) I could hit 440 or more as it is.
 
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The plumbing going into the skimmer is all 3/4"

I went with 1" from the pump and used a 1" to 3/4" reducer into the elbow up top.
 
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Oh, and with the 784 you will get microbubbles escaping. Though I haven't tried to adjust the inside inlets as I haven't worried about it as it doesn't come close to getting to the display through the rest of the sump.
 

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Ok, cool. Thank you for the info!

I'll step down from 1-1/2 or 1-1/4 from the pump to 1" for the flow meter, then down to 3/4 for the injector. I'll see how that goes for a while. I can always move up to a 800 series down the road. I'm probably 90% sure this is the way I'm going to do it. Tomorrow I'm going to post the flow specs of several of the injectors for comparison so everyone can see the differences.

With my sump the skimmer will return into the same chamber. The rest is very similar to yours, just a bit bigger. Bubbles will be no issue.
 

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Below is the listed flow specs for several injectors. I'm listing these because I think it's safe to say Mazzei has done thorough job testing them, more so than we are currently capable of doing. I'm also only posting the psi up to 25 because it's highly unlikely any of us are going to see pressures much above that. (Without a pressure gauge in the pipe it's hard to tell for sure.) The green highlights are the approximate flow and air draw Jason is seeing with a DCP-18000 pump. These are derived from the gpm numbers he's seeing on the Neptune flow meter. Based on his numbers it looks like the pump is generating about 12psi at the injector. Given that it's very close to the same across the 684 & 784 I think that psi estimate is pretty close. But against these charts the air draw is much higher than the given psi estimate. I think what the pump is actually producing is more like 20psi. (More on this in the next paragraph) The numbers in parentheses are what the flow would be if the air supply is cut off. It would be interesting to see what flow he gets when the suction port is plugged, it would help verify this psi estimate. I believe the higher air draw he is getting is due to the 1/4" tubing adapter, washer, ball and spring being removed from the injector while using 1/2" tubing for the air supply. This supplies more air and less water in the output.

As you can see from the charts, these injectors are very dependent on the supply psi to the water inlet while having very little to no back pressure on the outlet side. Ok, so why am I posting all of this you ask? Take a look a the yellow highlighted cells. At the same psi the flow drops on the 1" injectors compared to the 3/4, you have to get to the 1078 model before the flow is higher than the 784 at any given psi. My thoughts on this are that the modest increase in flow rating between the 878-978 is reduced do to the much higher air draw these models have. The air inlet on the 1" injectors is threaded 3/4" and it's 3/8" on the 3/4" injectors. In essence there's so much more air being pull in that less water makes it through the injector as this is also what were seeing in Jason's numbers with the parts removed from the air inlet on the 684 & 784.

The problem I see in testing one of these larger injectors is the need to replace all the piping after the injector all the way to the discharge inside the skimmer. At least to the Tee where there could be less restriction with two 3/4" outlets. If that piping isn't stepped up to 1" there will be back pressure applied to the injector outlet. And you can see what that does to the air draw. Doing this would mean needing to enlarge the hole in the base acrylic so the fittings will be able to be changed out. Hmm, that's a one way trip from the looks of it. It would require a good bit of modding to go back to 3/4".

So is it all worth it? Is there such a thing as to much air/bubbles in a 8" tube? Would there be a height restriction on one designed around a 1" injector. I don't know the answers to these questions. Maybe Jason and I could talk Jeff at MTC to make us a base with 1" fittings for testing. Beyond that it sounds like a lot of work and maybe the 784 is where we call it quits.

Anybody else have any thoughts?

Injector Preformance Comparison.jpg
 

anit77

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I had a nice talk with Jeff at MTC yesterday. Yes, there can be too much air. ;)

He said the if you move up to a one inch injector that you'd be better off getting and HSA1000 skimmer at 48", or a custom taller one, that the neck on the MVX is going to be too short. The volume of air would just be too much for the MVX with the shorter neck. He also said that the holes and fittings on the MVX would not accommodate 1" plumbing and the HSA with the lower chamber would be better suited for it and that those also can come with a larger gate valve installed to handle the increased water flow.

I'm sticking with a 48" MVX, he's drilling the top plate for me for a Swabbie and I'm getting a quick change head. I'll probably give the top chamber plate a good rinse when cleaning but with the quick change it will be easier to get it in the sink. To power it I'm going to stick with the DCP18000/784 combo that Jason is using.

I'm really looking forward to getting it installed. I'm using a Reef Octopus now and whenever I feed frozen it kills the foam head for 3 to 4 hours. I also need the PH help. My entire system, including the display, is in my basement. I've run an outside air line and it's helping some but with this I'm hoping that it will be even better.

Thanks again for the detail you put into documenting everything here Jason. It's been a big help!!!
 

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Below is the listed flow specs for several injectors. I'm listing these because I think it's safe to say Mazzei has done thorough job testing them, more so than we are currently capable of doing. I'm also only posting the psi up to 25 because it's highly unlikely any of us are going to see pressures much above that. (Without a pressure gauge in the pipe it's hard to tell for sure.) The green highlights are the approximate flow and air draw Jason is seeing with a DCP-18000 pump. These are derived from the gpm numbers he's seeing on the Neptune flow meter. Based on his numbers it looks like the pump is generating about 12psi at the injector. Given that it's very close to the same across the 684 & 784 I think that psi estimate is pretty close. But against these charts the air draw is much higher than the given psi estimate. I think what the pump is actually producing is more like 20psi.

Injector Preformance Comparison.jpg
FWIW, you can ignore everything on those charts above 15psi if you are going to be using the DCP18000. Shut-off is 30ft (12.9psi).
 

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